Focusing and centering device for cathode-ray tubes



M. R. HEPPNER 2,581,657

FOCUSING AND CENTERING DEVICE FOR CATHODE-RAY TUBES Jan. 8, 1952 3 She.e-tsSheet 1 Filed July 26, 1950 INVENTOR. Myron R. Heppner arronmzvs 1952 M. R. HE'PPNER 8 ,657:-

FOCUSING AND CENTEIRING DEVICE FOR CQTHODE-RAY- TUBES Filed July 26, 1950 I 3 Sheets-Sheet 2 FIG. 6.

FIG].

- INVENTOR. M yron R. Heppner ATTORNEYS Jan. 8, 1952 M. R. HEPPNER RAY TUBES FOCUSING AND CENTERING DEVICE FOR CATHODE- Filed July 26, 1950 FIG. 8.

3 Sheets-Sheet 3 FIG.9. 54 52 56 WHHHHHWU INVENTOR Myron R. Heppner W, 9umaml PM AT ORNEYS |IIHHIHICH HHW 11 FIG. 10.

Registered Jan. 8, 1952 UNITED STATES PATENT OFFICE .FOCUSING AND CENTERING DEVICE FOR CATHODE-RAY TUBES Myron R. Heppner, Round Lake, Ill.

Application July '26, 1950, Serial No. 176,033

ii-Claims. 1

This invention relates to improvements in a device for centering and focusing an electron beam in a cathode ray tube upon the fluorescent screen of said tube, and refers particularly to a device of this character which may be mounted upon the external portion of the neck of the tube.

One of the important features of the present invention resides in the provision of a permanent ring magnet which is adapted to embrace the neck of a conventional cathode ray tube, "and a magnetic short :circuiting device which may be adjustably moved with respect to the permanent magnet to vary the field strength :of the magnet and thus provide a convenient means :for focusing'the electron beam upon the fluorescent screen of the tube.

Another important feature of the present .invention resides in a ferromagnetic ring for centering the electron beam with respect to the geometrical center of the tube screen which functions substantially independently of, anddoes not disturb, the main focusing field, manipulation of the centering device not distorting the picture upon the screen in .the manner of many centering devices heretofore proposed.

.A further important feature of the presentinvention resides in a focusing and centering device of the class described which is economical in construction and is simple in operation.

Other features and advantages of the present invention will be apparent from the accompanying drawings and following detailed description.

In the drawings,

Fig. l is a side elevational view of a conventicnal cathode ray tube having my improved focusing and centering device mounted on the neck of the tube.

Fig. 2 is a sectional view taken on line '2-2 of Fig. 1.

Fig. 3 is a fragmentary sectional view taken on line '--3 of Fig. 2, parts being brokenaway and parts being shown in section.

Fig. 4-15 a detailed sectional view illustrating the universal mount for the centeringrod'.

Fig. 5 is a detailed sectional view taken on line 5-5 of Fig. 4.

Fig. 6 is a sectional view taken on line 6-45 of Fig. 2.

Fig. 7 is a rear eievational view of the device showing the manner in which the centering device may be eccentrically adjusted relative to the magnet and short circuiting cup.

Fi 8 is a front elevational view of a modification of the present invention.

Fig. 9 is a sectional view taken on line 9-9 of'Fig. '8. I

Fig. 10 is a sectional view taken on line [EL-i B of Fig. 9.

Fig. 11 is a sectional View taken on line H--H of Fig. 8.

Referring in detail to the drawing, 1 indicates a conventional cathode ray tube having an enlarged front portion 2 and a neck portion 3. The tube .1 carries the usual fluorescent screen 4 at its front end and is provided with the usual base portion :5 at its rear end, the base portion carrying a plurality of contacts 5 whereby appropriate connections may be made to the tube. My improved focusing and centering device 1 is adapted to be mounted upon the neck 3 of the tube l and for purposes of description that end of the device 1 closest to the screen 4 will be hereinafter referred to as the front of the device and that portion of the device closest to the base 5 will be hereinafter referred to as the rear of the device.

The device 7 comprises at its front end a plate 8 which is constructed of a ferromagnetic material. The plate 8 is provided with a central aperture 9 wherebysaid plate may be positioned in embracing relationship with respect to the neck 3 of the tube "I. That portion of plate 8 which defines aperture '9 is offset as at it in Fig. '2, the offset portion providing a seat for a ring magnet H. The ring magnet It may be of the usual aluminum-nickel-iron type commonly known as Alnico.

An annular ring [2 having an inwardly extending annular flange 12', embraces one end of the ring magnet H. Ring supports it are formed integral with the ring l2 on diametrical opposite sides thereof, the ends of said supports being secured to the plate 8 by any suitable fastening devices, preferably rivets It. The ring magnet is thus firmly secured to plate '8.

Referring particularly to Figs. 6 and 7 a supporting bracket 15 is secured to the rear face of plate 8 by means of rivets or the like l6, said bracket having an inwardly extending supporting portion IT. The bracket [5 is Preferably constructed of a non-magnetic material such as brass, copper, aluminum, or the like. A rod I8 is positioned in an aperture I9 provided in the supporting extension 11, said rod being loosely positioned with respect to said support. One end of said rod is of restricted diameter as indicated at 20 and is positioned in an aperture 21 in plate 8. The end '20 of the rod I8 is peened so as to permit rotation of the rod, but prevent axial movement thereof with respect to the plate. A collar 22 circumscribes the rod l8 adjacent the rear face of the support ll whereby axial movement of the rod 8 relative to the plate 8 and support ii is prevented. The extending end of rod i8 is knurled and is also provided with a slot l8 whereby said rod may be conveniently rotated.

A cup-shaped member is positioned in circumscribing relationship with respect to the magnet II. The member 23 comprises an annular wall 24 which terminates in an inwardly extending annular flange 25, the wall 24 being spaced from magnet H. A sleeve 25 is secured at one end in aperture 21 provided in the flange 25, said sleeve being immovable with respect to the flange. The internal portion of the sleeve is provided with screw threads adapted for engagement with external threads 27' formed upon the outer surface of rod 18 between the plate 8 and support".

Diametrically opposite from rod 18 a guide pin 28 having a head 29 is rigidly secured to plate 8. Adjacent the rear face of the plate 8 the guide pin has an enlarged portion 35. The opposite end of pin 28 is positioned in slot 3| provided in that portion of flange 25 which is diametrically opposite from sleeve 25. A coil spring 32 embraces pin 28 and is confined between the enlarged portion of said pin and flange 25.

The cup-shaped member 23 is constructed of a ferromagnetic metal. As will be hereinafter more fully described the cup-shaped member 23 provides a magnetic short circuit for the magnet H.

A ring 33, constructed of a ferromagnetic material, is slidably positioned upon flange 25, the ring 33 carrying a radially outwardly extending lug 34. Lug 34 is provided with an elongated slot 35 and a screw 36 embraced by a spring washer 31 passes through slot 35 and is threadedly positioned in flange 25. If desired the screw 36 and washer 31 may be replaced by a rivet whose head is spaced from flange 25.

Diametrically opposite the lug 34 ring 33 carries a radially outwardly extending actuating lug 38. Lug 38 is provided with an aperture 39 in which a control rod 45 is loosely positioned. A socket 4| (Fig. 4) having a plurality of spring pressed fingers 42 is carried by plate 8 and the end of control rod 45 terminates in ball 43 which is positioned within the socket, the arrangement being such that rod may be rotated about its axis or may be pivoted a limited distance about the ball 43 within the socket. In view of the fact that an intermediate portion of the control rod is in contact with the lug 38 swingable movement of the control rod results in slidable movement of the ring 33 parallel to the face of flange 25, it being possible to move the ring 33 in substantially any direction in the plane parallel to the annular flange 25. Lug 38 is also provided with a slot 38' in which the end of pin 28 projects, said slot functioning to limit movement of the ring 33. A strip fill is carried upon flange 25 and functions to prevent unintended removal of ring 33 from flange 25.

In operation, the device 1 is positioned upon the neck 3 of the cathode ray tube I, the interior diameter of the magnet H being larger than the exterior diameter of the neck 3. The plate 8 is provided with bolt holes 44 whereby the plate, carrying the elements hereinbefore described may be mounted upon a suitable support 45', which may conveniently be one of the tube supports for mounting the tube in the chassis.

The magnetic lines of force which emanate from the magnet 3 and pass through the neck portion of the tube are dependent upon the permeability or susceptibility of the environment adjacent the magnet. By the provision of the cup-shaped member 23 constructed of a ferromagnetic material a greater or lesser amount of magnetic flux may be diverted through the cup depending upon its position with respect to the magnet. By rotating rod IS the cup-shaped member 23, which in effect is a short circuiting device for the magnetic flux, may be moved axially with respect to the magnet In this fashion the effective strength of the magnet H with respect to the field which it produces within the cathode ray tube neck may be changed. By this means a convenient focusing device is provided for the proper focusing of the electronic beam upon the fluorescent screen 4.

To center the electronic beam upon the fluorescent screen rod 43 may be manipulated to change the position of ring 33 with respect to the annular flange 25. As shown in broken lines in Fig. '7 rod 45 may be so manipulated as to dispose ring 33 in substantially any desired eccentric position with respect to the annular flange 25. In this fashion the magnetic field established by the short circuiting cup 23 may be distorted or altered thereby tending to alter the position of the electron beam within the tube. It will be noted that the alteration in the magnetic field is brought about by a change in the effective flux path of the short circuited flux and in this fashion the proper centering of the beam may be brought about without materially distorting or changing the focusing adjustment since the distortion is brought about in the short circuited field rather than in the main field.

Referring particularly to Figs. 8 to 11 inclusive, a modification of the invention is shown, wherein 45 indicates a ferromagnetic plate, similar to plate 8 and having a central aperture 45. An offset seat 41 is formed adjacent the defining edge of aperture 46 for the reception of a permanent magnet 48, similar to magnet l I. Magnet may be carried by a tubular member 49 having an annular flange 50 for abutting the rear face of the magnet. The front portion of the tubular member is expanded outwardly, as indicated at 5| in Fig. 9, whereby to secure the tubular member carrying the magnet to plate 45. The tubular member 49 is constructed of aluminurn, brass or other non-magnetic material.

A cup-shaped member 52, similar to the memher 23 hereinbefore described circumscribes magnet 48 and functions as a magnetic short-circuiting device for a portion of the flux from the magnet. The cup-shaped member 52 carries an inwardly extending flange 53 in which a threaded sleeve 54 is retained, the sleeve cooperating with adjusting screw 55 to axially move the cupshaped member relative to the magnet to control the focusing of the electron beam, as hereinbefore described. Screw 55 is supported by bracket 55 and one end of the screw is journaled in plate 45, similar to the arrangement hereinbefore described in conjunction with screw 21. Diametrically opposite screw 55 a pin 5'! is carried by plate 45 and extends through opening 58 in flange 53. A coil spring 59 embraces pin 5'! and functions to bias that portion of cup 52 opposite to screw 55 so as to secure uniform scanner can movement of all eportionsvof the cup when thescrew 55 is-manipulated.

:annular ferromagnetic plate 80 :is secured by means of screw 6 to flange '53. It has been found that an increase in the sectional path of the leakage flux at this zone .is advantageous :in focusing the beam. The plate 60 is preferably concentric with the flange opening, but if desired it may be rendered eccentric thereto by the-manipulation ofscrew fi I.

As a feature :of the present form :of "the in vention an annular collar 62 is s'lidably carried upon the inner surface of plate 4.5. The :collar is constructed of a ferromagnetic material and carr-i'esan inwardly extending annular flange 63 1 the interior diameter of which :is greater than the exterior diameter of the :magnet 48 whereby the flange 63 of the :collar may beradially spaced from the outersurfa'ceoi the magnet. 'Theco'llar 82 also carries anannular flange .64 which contacts the surface of aplate45 :and is disposed parvallel to said surface. The flange '64 carries a Tongue 5, provided avitlnasslot 66 which is engageablewith guid pin 61 carrled iby plate 45. Diametrically opposite fromtongue 65, theLfiange 64 carries a manipulating extension or handle 158. A slot .68 is provided in the extension 6.8 :whereby said collar can b :slidably moved in all directions a limited distance without being :o'bstru'cted by pin 51. .A second slot 1.0 :is provided in extension 65 and a guide plate H is slidably positioned upon the extension, said guide plate also being provided with slot :72 of relatively restricted 'width. A screw 13 :is carried by plate 415 andextendsthrough both slots in extension .58 and slot 12 :in iguicle plate H, :said screw serving as a guide to the transversenn'ovementof the extension.

The movable collar 82 may be employed as a centering device for the electron beam, functioning, ineffect as an independent eccentrically movable short-circuit for flux other than the flux within the magnet confines, that is, the main flux field. The collar maybe moved in a direction longitudinal with respect to finger 65 and extension .68, .the movement being guided by screw 6,! in slot v(iii, and extension 68 slidably moving with respect to screw 73 and guide plate II, .or the collar .may b :moved by moving the extension :58 transversely whereby the movement will he guidedbyscrew 13 in.s1ot.1 2. In all-cases, however, the .mcvement .is so constrained as to prevent contact .of the .collar :62 and the mag net 4.8.

It has :been .found in devices heretofore proposed for focusing and centering an electron beam that when the beam is :properly focused, the operation .of centering the beam results :in distortion of the circular beam upon the screen, usually rendering it more or less oval. In the present-device, after the beam has been properly focused "the circular beam may be moved, by manipulating the centering adjustment without altering or distorting the circular contour of the beam on the screen. This is believed to be brought about by the fact that the flux "employed in centering in all cases constitutes short-circuited flux and does not require substantial interference with the main focusing flux within the ring magnet.

It can readily be seen that herein is provided a device which is of economical construction; can be readily mounted upon a conventional cathode ray tube; is simple to manipulate, and performs the function of focusing and centering the elec- 6 tron beam without E'havin'g ithe centering adjustment materially interfere :with the focusing radiustment.

I claim as my invention:

"1. In a focusing and centering :device for an electron beam in a cathode ray tube-which comprises, a frame, a permanent magnet :carried by said frame for embracing 'a portion of the neck of a cathode ray tube and establishing a "main magnetic new, :a "magnetic shortcircuiting device carried by said framein circumscribing :relationship with respect to-and spaced from a portion of said magnet, means for changing the position of said short-circuiting device with respect to said magnet along thelength of the tube neck'to change the main magnetic field in the tube to focus the electron beam, and means magnetically contacting said short-circuiting device for laterally changing the 'short-circuite'd flux .p'ath relative to the axis of the neck of the tube to center the electron beam passing through said neck upon the screen of the tube.

2. In a "focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame, a permanent magnet carried by said frame for embracing a portion of the neck of a cathode ray tube and establishing a main magnetic field, means for establishing a shortcircuitmagnetic path of relatively low reluctance radially spaced outwardly from said magnet, means 'for changing the effective reluctance of said short-circuit path to change the strength of the main field and focus the electron beam passing through the neck of the tube, and 'm'ov ableierro-magnetic'means contacting said-shortcircuiting means for radially changing a portion of the short-circuit path to center the electron beam passing through the neck of said tube upon the screen .of the tube.

13.. In a focusing and centering device for an electron beam a cathode ray tube which comprises, a frame, .a permanent magnet carried by said frame for embracing a portion .of the neck .of a cathode ray tube, .a.magne'tic short-circuit ing device carried bysaid frame in circumscribing relationship with respect to and spaced from a portion of said magnet, means for changing the position of said short-circuiting device with respect. to said magnet along the length of the tubeneck to change the-strength of the magnetic field in the tube to focus the electron beam, and a :ferro-magnetic ring adapted to embrace the neck of the tube and carried by said short-circuiting device for eccentric movement relative thereto and relative to the neck of the tube for centering the electron beam passing through the neck of the tube.

4.;In1a:'focusing and centering device :for an electron ibeam in arcathode ray tube which com prises, -:a frame, :a permanent ring magnet carried by said frame for embracing a portion .of the neck of a cathode ray tube, .anannular magnetic :short-mircuiting device carried by said frame in circumscr'ibing relationship with respect to and spaced from a portion of said magnet, means for changing the position of said short-circuiting device with respect to said magnet along the length of the tube neck to change the strength of the magnetic field in the tube to focus the electron beam, and a ferro-magnetic ring adapted to embrace the neck of the tube and carried by said annular short-circuiting device in magnetic contact therewith and for eccentric movement relative thereto and relative to the neck of the assme'z' tube for centering the electron beam passin through the neck of the tube.

5. In a focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame, a permanent ring magnet carried by said frame for embracing a portion of the neck of a cathode ray tube, an annular magnetic short-circuiting device carried by said frame in circumscribing coaxial relationship with and spaced from a portion of said magnet, means for moving the said short-circuiting device axially with respect to said magnet along the length of the tube neck to change the magnetic field in the tube to focus the electron beam, and a ferromagnetic ring spaced from said ring magnet and adapted to embrance the neck of the tube, said ferro-magnetic ring being carried by and in magnetic contact with said annular short-circuiting device for eccentric movement relative thereto and relative to the neck of the tube for centering the electron beam passing through the neck of the tube.

6. In a focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame constructed of ferro-magnetic material, a permanent ring magnet carried by said frame and adapted to embrace a portion of the neck of a cathode ray tube, a magnetic shortcircuiting device, non-magnetic support for carrying said device upon said frame in circumscribing coaxial relationship with and spaced from a portion of said magnet, non-magnetic means for changing the position of said short-circuiting device with respect to said magnet along the length of the tube neck to change the magnetic field in the tube to focus the electron beam, and a ferromagnetic ring adapted to embrace the neck of the tube and carried only by and in magnetic contact with said short-circuiting device for eccentric movement relative thereto and relative to the neck of the tube for centering the electron beam passing through the neck of the tube.

7. In a focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame, an annular magnet carried by said frame for embracing a portion of the neck of a cathode ray tube, a cup-shaped magnetic short-circuiting device having an inwardly extending annular flange carried by said frame in clrcumscribing coaxial relationship with and spaced from a portion of said magnet, means for changing the axial position of said short-circuiting device with respect to said magnet along the length of the tube neck to change the strength of the magnetic field in the tube to focus the electron beam, and a ferro-magnetic ring adapted to embrace the neck of the tube and slidably mounted upon and in magnetic contact with the annular flange of said short-circuiting device for eccentric movement relative thereto in the plane of said flange and relative to the neck of the tube for centering the electron beam passing through the neck of the tube.

8. In a focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame, an annular magnet carried by said frame for embracing a portion of the neck of a cathode ray tube, a, cup-shaped magnetic short-circuiting device having an inwardly extending annular flange carried by said frame in circumscribing coaxial relationship with and spaced from a portion of said magnet, means for changing the axial position of said short-circuiting device with respect to said magnet along the length of the tube neck to change the magnetic field in the tube to focus the electron beam, a ferro-magnetic ring adapted to embrace the neck of the tube and slidably mounted upon the annular flange of said short-circuiting device for eccentric movement relative thereto and relative to the neck of the tube for centering the electron beam passing through the neck of the tube, and an actuating rod pivoted to said frame and connected to said ring for sliding said ring upon the flange of the short-circuiting device.

9. In a focusing and centering device for an electron beam in a cathode ray tube which comprises, a frame, a permanent ring magnet carried by said frame for embracing a portion of the neck of a cathode ray tube and establish a, main magnetic field within said ring in the neck of the tube, means for establishing a short-circuit magnetic path radially spaced outwardly from said magnet, said means comprising a, ferro-magnetic annular member circumscribing and spaced radially outwardly from said magnet, and a ferro-v magnetic collar carried by said annular member and circumscribing said tube neck and spaced axially from said magnet, means for axially moving said annular member to focus the electron beam of the tube, and independent means for eccentrically positioning said collar to center the electron beam.

MYRON R. HEPPNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,149,101 Ploke Feb. 28, 1939 2,200,039 Nicoll May 7, 1940 2,234,720 De Tar Mar. 11, 1941 2,259,531 Miller et a1. Oct. 21, 1941 2,336,837 Bedford Dec. 14, 1943 2,416,687 Fry Mar. 4, 1947 2,418,487 Sproul Apr. 8, 1947 2,431,077 Pooh Nov. 18, 1947 2,433,682 Bradley Dec. 30, 1947 2,442,975 Grundman June 8, 1948 2,533,687 Quam Dec. 12, 1950 2,533,688 Quam Dec. 12, 1950 2,533,689 Quam Dec. 12, 1950 FOREIGN PATENTS Number Country Date 462,683 Great Britain Sept. 1, 1936 472,165 Great Britain Sept. 13, 1937 521,439 Great Britain May 22, 1940 597,255 Great Britain Jan. 21, 1948 615,553 Great Britain Jan. 7, 1949 

